Interlock for couplings and supports for trailers



w. BNNETT 2,417,904

' Filed Feb. 24, 1945 2 sheets-sheet 1 INTERLOCK FOR COUPLINGS AND SUPPORTS FOR TRAILERS a. .1.. ,m 7 5 H ,www w@ f p. 4mr WMI {la} fr. l l f J6 f J 2 2 a l f, i. ,Z. d v 55556@ n 044 m anfw 0 65 1. 0 .2 f 7 0 fill I 7 6 2u 2 2 (v fw 1 )Il z r fr 9 O 9 \O 0 2 l, f 2 4 4 ..1 ....IIJ I .l 6 7 ../0 l .4 .w 9W f wir 1: l FIL lMarch 25,

March 255', 1947. w. BENNETT INTERLOCK FOR COUPLINGS AND SUPPORTS FOR TRAILERS 2 Sheetsi-Sheet 2 Fi 1ad Feb.- 24, 1945 Fatented Mar. 25, 1947 KTERLOCK FOR COUPLNGS SUPPR'ES FR TRAILERS Walter Bennett, Los Angeles, Calif., assigner to Utility Trailer Manufacturing Company, Los Angeles, Calif., a corporation of California,

Application February 24, 1945, Serial No` 579,570 is cams. (ci. asc-33.1)

l 'Ihis invention has reference to mechanisms for cooperatively interlocking the operation of semitrailer supports and coupling mechanisms. The

general purpose of the invention is the provisionV of an improved and simplified form of interlocking or controlling mechanism which is. generally applicable to various types of coupler elements and also various types of support mechanisms. Among other objectives, it is the purpose of the present invention to provide a simplified form of interlocking mechanism which will not only effectively interlock the coupler and the support, but also will have the additional function of forcing the support into its supporting or locked condition, byvirtue of opening movement of the coupler.

Patent No. 2,355,775 issued August 15, 1944 to Robert M. Barnhart et al., sets out an interlocking fand cooperative mechanism which'in some general functions is similar to the mechanism of my present invention, and cn which my present invention is, in certain of its aspects, an improvement. That patent sets out a mechanismr wherein a control member, moving with the trailer support, locks the draft coupler closed and prevents its opening until the support has been lowered into its supportingpositon. And then, when the coupler is opene vits opening causes the control member and the support to be locked in trailer supporting position as long as the coupler is open. l

My present improved interlocking mechanism also performs those functions, with a mechanism of improved and simplified form and mode of operation, and it also performs an additional function.

In my improved mechanism the coupler is held against release or opening as long as the support is in an upper or non-supporting position. On movement of the support from its non-supporting position toward its supporting position, the coupler is released so that it can be opened; but the inter-action is such that the coupler cannot be opened to relase the king pin or other elements of the draft combination without necessarily and positively moving or forcing the support into its fully effective supporting condition. In other words, in the inter-related movements of the support and coupler as the supportmoves away from its non-supporting' condition and toward its supporting condition, the movement of the support releases the coupler for opening.-

That release may take place before the support has finally reached an effective supporting condition. But after that release has taken place,

the inter-action of the parts is such that the coupler cannot open to release the king pin without first positively moving or'forcing the support into its full supporting condition. And it is also a feature of this inter-action that the support is forced into full supporting condition, and locked in that condition, at a time in the opening movement of the coupler when the coupler' is still substantially and eifectively closed and has a relatively long movement to make before finally releasing the king pin. y

The present application is directed to my improvements in interlocking mechanisms used as an inter-control between any suitable type of coupler element and any suitable type ofl trailer support; being directed mainly to my improved cooperative interlock mechanism per se, regardless of the type of support which is to be controlled and operated. A companion application, Ser. No. 579,569, filed by me on even date herewith, is directed more particularly to a certain type of trailer support, in and of itself, -and to the'cooperative combination of that type of support and an interlocking a'nd cooperating mechanism of the type herein described.

For the purpose of the following description of a. typical and illustrative form of my invention, reference is had to the accompanying drawings in which:

Fig. 1 is a plan of the forward part of asemitrailer frame, showing a typical coupler with my improved interlocking and controlling mechanism applied thereto, the coupler being shown in its closed position in which it receives and locks the coupler element or king pin of a tractor;

Fig. 2 is a similar view showing the parts in the positions taken when the coupler is open;

Fig. 3 is a fragmentary detail section taken as indicated by line 3 3 on Fig. 1 and showing certain parts in the position indicated in dotted lines in Fig, 1;

Fig. 4 is a 'diagrammatic view at a relatively reduced scale showing a typical trailer support; and

Figs. 5 and 6 are diagrammatic views showing modifications of the interlocking mechanism.

The general arrangement and cooperation. of a tractor or towing vehicle and a semi-trailer are well known and need no particular description or illustration here. In combinations of one usual type to which, among others, the invention ap plies, the tractor and the trailer are provided with inter-engaging and interlocking coupler or draft lock elements which are engaged and locked together when the tractor backs under and -lifts the forward end of the trailer. The inter-engaging coupler elements usually include a king pin and a draft lock or coupler adapted to take the king pin; the king pin being mounted on the tractor and the draft lock or coupler on the trailer, but not necessarily so. That arrangement is used in the present typical illustration of the application of my invention.

Also, the coupler or locking elements which directly engage the king pin are of various types and kinds; and my invention is generally applicable to the various types of coupler element. A swinging coupler jaw is here chosen for a typicaljapplication of my invention.

A temporary support for the semi-trailer usually and desirably embodies a support device mounted on and under a forward part of the trailer frame, and which may be raised and lowered with reference to the trailer frame by some suitable arrangement or by some suitable means. The particular type or design of the movable support, and the means by which it is raised and lowered are, generally, of no importance in the present invention. The support may move into and out of its supporting condition in any suitable manner; may be locked, if desired in its nonsupportingcondition in any suitable manner; and may be moved between its two positions either manually or by some power operation. The support shown in Fig. 4 is intended merely to be typical. The trailer framing as here shown is also intended to be merely'typical. So-called frameless trailers are now being made; so, when I refer to a trailer frame I mean to include in that term any structure, such as a body, which performs the frame function.

In Fig. 4 a supporting leg or pair of legs are shown at i pivoted at their upper ends at II to trailer frame I2. A toggle linkage I3 is connected between legs I0 and an operating shaft I4 journaled on the trailer frame. The shaft may be oscillated Vby any suitable means, actuated either manually or by power, to move the support mechanism between the position shown in full and dotted lines. A fluid pressure actuated means I5 is here shown, to be operated in this particular instance by vacuum. Vacuum is applied via pipe I6 to actuating diaphragm I1 which is connected by rod I8 to an arm I9 on shaft I4. When vacuum is applied the parts are swung to the position shown in dotted lines, and continued application of vacuum holds the support in its upper or non-supporting position, this being the normal position during road travel of the coupled tractor and trailer. When it is desired to uncouple the tractor from the trailer and to leave the trailer supported independently, the supporting legs are lowered by cutting oi the application of vacuum, when the legs may simply drop under gravity to or toward the full line position. Or spring I8a or any other forcing means may aid in that operation; for instance a double acting vacuum` or pressure cylinder may be used at I5.

When the legs reach their nal effective supporting position, they may preferably be somewhat past a vertical line through pivot II. And they may also be locked and rigidly heldin their fully effective supporting position by the extended linkage I3 and its shouldered knuckle I3a which, as illustrated, may swing slightly past center in reaching the final position. In such a support mechanism as here illustrated, if the support does not reach its nal supporting position or its final locked condition by merely dropping under gravity, a nal forced rotation of operating shaft I4, counterclockwise in Fig. 4, may rlnally positively move or force the support into its nal and fully effective supporting condition, and/or nally lock it in that condition. Among other things, it is one of the functions of the interlocking and controlling mechanism, now to be described, to positively move or force the support into its final and fully effective supporting and/or locked condition before the coupler can be opened.

For inter-connective and interlocking purposes a connecting rod 20 is pivotally connected at 2I to an arm 22 mounted on the operating shaft Il; connecting rod 20 being in the rearward dotted line position shown in Figure 4 when the support l0 is raised to its non-supporting condition. When the support I0 is in its fully operative supporting condition, connecting rod 20 will be in the forward solid line position of Figure 4. This connecting rod is merely typical of a connecting means or linkage between the support mechanism and the interlocking and controlling mechanism shown in Figs. l and 2. The forwardiend of the same connecting rod 20 is shown in Figs. 1 and 2, Fig. 1 showing the connecting rodin its rearward position, corresponding to the rearward position shown in Fig. 4, and Fig. 2 showing rod 2B in its forward position, corresponding to the forward position shown in Fig, 4. The scale of Figs. 1 and 24s twice thatv of Fig. 4, insofar as the showing of the movements of connecting rod 2li-is concerned.

As shown in Figs. l and 2 the numeral 25 designates the typical king pin which is mounted upon the towing vehicle. The draft lock is here shown as mounted upon the trailer and is also here shown in a typical and illustrative form which embodies a coupler jaw or king pin locking mer'nber 26 pivoted at 2'I on a plate or other similar member 28 which forms a part of the trailer frame. The pivoted coupler jaw 26 swings between the closed position shown in Fig. 1 and the open position shown in Fig. 2, and is preferably latched and locked in its closed position by a spring-pressed latch bolt 29. In the typical and illustrative form 'herein described the draft lock includes both the coupler member 26 and the latch 29 but either one or both such members may be used, as will appear, and other forms of draft lock may be used. And as will appear later,

`the coupler jaw 2E (the member which directly locks the king pin) is also independently locked closed by the interlocking mechanism, so that if desired latch 29 may be entirely dispensed with. However the latch bolt, releasable manually, is a desirable feature of such a typical draft lock combination, as here described.

The latch bolt 29 is herein shown as being pressed forwardly by a latch spring 30 and as being projected by a latch lever 3| whose movement from the position shown in full lines to that shown in dotted lines in Fig. l, withdraws latch bolt 29 to a position where its beveled nose 29a is in the position shown in dotted lines in Fig. 1. The latch lever and latch are withdrawn to the dotted line position, against the action of spring 30, through the operation of a latch cooking bar 35, connected at one end to latch lever 3| and extending forwardly and through an opening 36 in frame member I2a. Bar 35 has a lug or hook 31 on its upper face, and in its withdrawn position, shown in Fig. 3. and in dotted lines in Fig. 1, this hook lug may be hooked up over the upper edge of opening 36, or over a projecting lug 35a at that upper edge.

In this partially withdrawn position of the 'latch bolt, nose 25a of coupler jaw 26 will engage the rear beveled face 29a ofthe latch as the r coupler jaw swings toward its open position of Fig. 2, impelled by the forward movement of king pin 25 as the king pin moves forwardly through slot d@ in plate 28. As coupler jaw 26 swings forwardly engaging its nose 26a with latch bevel 29a, it momentarily pushes` the latch a little further back from the dotted line position shown in Fig. l, moving cooking bar 35 forwardly so that lug 5l is disengaged from lugv 35a and drops away from it. Then, immediately the coupler jaw has swung past the latch bolt in its movement toward the full open position of Fig.' 2, the latch bolt immediately moves to its normal fully extended 'position shown in Fig. 2.

When the king pin has been fully removed, the vparts are left in the position shown in Fig. 2 and remain in that position until the king pin is reinserted and moved backwardly through plate slot dii. To insure the coupler-jaw remaining in that open position a light spring .di may be used, but may not Ibenecessary. Upon re-insertion, the

' arm 50 ls of no particular importance; I have king pin moving yback through slot 60 engages an extension 52 of coupler jaw 25, and by that engagement the king pin 'swings the coupler jaw back to its closed position as the king pin moves toward and against the closed rear end 50a of slot 40. In this closing movement, a beveled face 2Gb on the rear side of the nose end of the coupler engages the beveled end of latch 29 and pushes the latch bolt back as the coupler swings past it.

Latch spring 30 then springs the latch bolt in front of coupler 26 to lock it closed.

The draft lock mechanism which. has been so [far described is not, in land of itself, a part of my present invention, but is typical of draft locks and of king pin locking members to which my present invention is applicable. And while certain particular features of my present invention may be applicable more particularly to a swinging coupler or king pin locking member, as will appear, my inventions broader aspects are not necessarily limited to application to or combination with such a swinging coupler jaw. l

As applied in its preferred form to a draft lock embodying such a swinging coupler jaw, I now proceed to a description of the interlocking and controlling mechanism which cooperates the draft lock and the trailer support.-

A swinging control arm 50 is pivoted at '5| on plate 28 and `is coupled to connecting rod 2li by a suitable linkage so that control arm 5'swings between the two positions shown in Figs. l1 and 2 when connecting rod 20 takes the two positions shown the connecting rod equipped with a cross head guide 52 at its forward end to take a pin 01 roller 53 which is mounted on a bracket 54 on the upper faceof arm 50. In the arrangement here shown, cross head 52 is at a level above arm 50 so that locking head 55 can swing back and forth under the cross head.

A locking head 55 projects upwardly from the outer end of a connecting arm 56 which projects from the extension 62 of coupler jaw 26; so that locking head 55 swings with the coupler jaw, between the two extreme positions shown in Figs. 1 and 2. Connecting arm 56, as here shown, lies under control arm 5t, and locking head 55 projects' upwardly behind the rear edge face 5l of the control arm. In the position of Fig. 1 in which the coupler is closed on the king pin and the support isy raised to its non-supporting position, locking head 55 lies immediately behind rear edge face 5l at a pointrelatively close to pivot 5i of arm 50. The rear edge surface of arm 5t is arm 50 lies at a rather large angle to that line trol arm 50 need to be precise, excepting for the I fact that the lowered, effective supporting position of the support, or its locked position, will usually be somewhat precise, and the interconnectedcontrol arm 50 will therefore reach a more or less correspondingly precise position (Fig. 2)

when the support reaches its fully effective supporting condition. The nature of the connecting linkage between connecting rod 20 and control gi movement in a'position directly ahead of head The relationship of the parts when in the relative positions of Fig. 1 is. such that any force tending to hold control arm 50 toward the rear will have a relatively large leverage advantage over any force tending to move the coupler toward its open position and tending to move locking head 55 forwardly toward its corresponding position shown in Fig. 2. In the particular mechanism here being described, that advantage of the support raising force over any coupler opening force is due to either one or both oftwo things. In the 'position of Fig. 1 head 55 contacts, or substantially contacts, with the rear face of control arm 50 at a point quite close to hold control arm 50 in the position of Fig. 1.

To force arm 50 forwardly from the position of Fig. 1 head 55 must acton arm face 53 with a camming action; and the camming angle presented at 58 is suiciently large that, considering frictional losses, the face at 58 acts substantially as if it were a positive stop-substantially as if it were oriented at an angle of acrossthe arcuate path of movement of head 55-providing that there is any resistance at all to the forward swinging movement of control arm 50. Thus, with the parts in the relative positions of Fig. 1, the inter-action between head 55 and the rear edge face of control arm 50 maybe said to operate to give a support raising force a comparatively large or even virtually infinite advantage over any force tending to open the coupler.

In the position in which the coupler is open head 55 and control arm 50 lie in such positions as shown in full lines in Fig. 2. n the rear. ward side of its outer end arm 50 has an arcuate face 60 which, with arm 50 in the full line position of Fig. 2, is substantially concentric with coupler pivot 21 at the same radius from pivot 21 as the inner arcuate face 6I of locking head 55, which is also preferably concentric about pivot 21. While it is not necessary that both faces 6l! and 6l be concentrically arcuate, that arrangement is preferable; but it will suffice if one or the other is substantially concentric with pivot 21. The reason for the arrangement will appear later.

As control arm 50 swings from the position of Fig. 1 toward the position of Fig. 2 it will reach or pass through an intermediate position such as is shown in dotted lines in Fig. 2. In any such position of the control arm the outer portion 58a of the angular rear edge face 58 will lie ahead of locking head 55. But, as arm 50 swings around forwardly the angie of face 58 to the line of movement of head 55 decreases until, i

at some such position as is shown in dotted lines in Fig. 2, the camming angle between head 55 and face 58 has become small enough that an opening force applied to the coupler will swing head 55 on around forwardly and will cam the control arm 50 nally into the position shown in full lines in Fig. 2. The, changing relationship between the swinging arm 50 and cross-head 52 also plays a part in this action, as the forward movement of 52, per unit angular movement of 50, decreases as the position of Fig. 2 is approached. Arm 50 will reach its final full line position when .the forward part of arcuate face 6l of head 55 rides past the outer end of arm face 58 and first rides onto arcuate face 60 of the arm. From that point on in the movement of the coupler and head 55,r control arm 50 will remain stationary insofar as any movement caused by head 55 is concerned. It is not necessary to the interlocking action that arm 50 should swing further around toward the left; in fact my companion application shows a type of support which allows arm 50 to move on further after the support mechanism has reached afully effective supporting condition. But, in any event, the fact is that once head 55 has begun to ride over the arm face 60, the arm has necessarily been moved at least to the full line nal position of Fig. 2 and is thereafter positively locked from backing up from that position toward the position of Fig. 1.

In the relative positions shown in the dotted lines in Fig. 2 head 55 is close to the position where it begins to ride over arcuate arm face 60.

In that position coupler jaw 26 is still disposed across slot 40 and is still removed by a substantial swinging angle from its nal open position. The position of coupler jaw 26 which corresponds to the dotted line position of head 55 is also shown in vdotted lines in Fig. 2. Thus it will be seen that arm 50 must reach its final forward position, or be forced by the coupler into that final forward position, considerably ahead of the coupler finally reaching its full open position at which it will release the king pin. The arrangement is such that the coupler, and locking head 55, have a relativelylong swing to reach the open position after control arm 50 reaches its ultimate forward position. And that means that the support, which is necessarily in its fully operative, or finally locked position when arm 5l) is in its final forward position, is put into its nal trailer supporting condition definitely and by a large margin before the coupler can nally reach its open position.

So far it has been assumed that the support is held in its upper or non-supporting position the movement of arm 50 and have also shown it associated with latch lever 3| so as to be released at the same time that the latch is initially manually withdrawn. In a preferred form this releasable positive stop embodies a pivoted dog 10 normally held by spring 1i in a position where its nose 12 lies in the forward swinging path of the outer end of control arm 5U. A. shoulder stop at 13 prevents the dog nose 12 from moving to the left in Fig. 1, so that nose 12 thus becomes a positive stop to the forward movement of control arm 50. The position of the dog with relation to the arm is such that the arm can have no great forward swinging movement and therefore the support can have no objectionably large lowering movement until the dog is withdrawn.

A rod 14 is connected at one end to dog 10, passes loosely through a lug 15 on the outer end of latch arm 3| and has a head 16 at its end in such a relative position that, when latch arm 3l is moved to the dotted line position of Fig. 1, dog 10 is moved toits dotted line position where its nose 12 is thrown out of the path of arm 50.

The general cooperation of all the parts which have now been described may be summarized as follows. Assume first that the support is raised to its non-supporting position and that the coupler and other associated parts are in substantially the positions shown in full lines in Fig. l. In order to release the king pin it is necessary that two preliminary things should be done. It

is necessary, in the particular form of draft lock here used as an illustration, that latch 29 be ini that withdrawal of the latch also removes stop dog lo from its obstructing position in the path of control arm 50 and thus makes it possible to lower the support to or toward its supporting condition. The support' is then lowered by releasing the means which holds it up, and by allowing it to drop, or by forcing it,y to or toward i-ts fully operative supporting position. The support can be lowered, partially or completely,

without opening the coupler. Locking arm 56 in the position of Fig. l does not prevent control arm 50 from swinging to the position of Fig. 2.

Until the support has moved materially from its upper non-supporting position, and until control arm 50 has moved materially forward of its position of Fig. 1, the control arm eitherpositively locks the coupler closed, or to all practical intents and purposes does so if there is any appreciable force preventing or impeding the movement of the support into its fully operative supporting condition. The support may be prevented from reaching an' operative supporting condition` by striking an obstruction. such as a not already there.

9 high spot on the ground surface; vor may merely be impeded. as by friction of the moving parts.

Assuming that the support has reached a fully operative supporting condition and that control arm 50 has correspondingly reached its final position shown in full lines in Fig. 2, the coupler can then swing open unimpeded as the king pin is pulled forwardly. 'In this position, the control arm 50 is locked against movement in its support raising direction.

Assuming that the supportonly movesvpart way toward its'fully operative supporting condition, then it may or may not be possible to open the coupler, depending on two factors; viz. how

far the support and arm 50 have moved, and the magnitude of the force preventing or impeding that movement. If the support liasmoved only slightly, a relatively'slight impedingv force will prevent opening of the coupler. If the support has moved further and arm 50 has moved to some such position as the dotted showing in Fig. 2, a force which positively obstructs support movement will of course prevent coupler opening. And, in general, a larger movement obstructing force is necessary to prevent couplerl opening as the parts approach more closely to the full line position of Fig. 2. But in any event,

if the support is not in fully operative supporting condition, either the coupler is held from opening, or the opening of the coupler forces the support to fully operative condition. In no event can the coupler open without positively moving the support to that fully operative condition if it is And once the support is in fully operative condition, regardless of how it has reached that condition, the nal opening movement of the coupler locks it there well before the coupler is clear open.

'I'he coupler in its open position thus holds and locks the support in its supporting position; but the support in that position does not lock the coupler open. When the king pin-is backed in for coupling, the locking arm 56 swings from the position of Fig. 2 to that of Fig. 1 without the necessity of control arm 50 moving to its position of Fig. 1. In other words, closing the coupler does not necessitate raising the support, it being raised by its own independent raising means.

After the king pin is fully locked, with latch 29 holding coupler jaw 26 closed in the position of Fig. 1, the support can then be raised to its non-supporting position shown in dotted lines in Fig. 4. In so doing, controll arm 50 swings from the position of Fig. 2 to that of Fig. 1. Dog 'l2 at that time is in its full line position of Fig. 1, held in that position by spring 1|. .As arm 5l) swings past the dog it is momentarily thrown to the dotted line position of Fig. 1, allowing the arm to pass. Dog 12 then functions as a latch to hold arm 50 substantially in the position in which the support is up. preventing the lowering of the support until the dog is subsequently moved to its non-latching position by manual operation as before described. l

The function performed by the swinging control arm 50 and locking head 55 is, in general, the function of an interconnecting linkage acting between thecoupler or a part that moves therewith and the support or a part that moves with it, and having a variable leverage ratio as the parts change position. 'I'his linkage may be defined as one which, in the position of Fig. 1 gives a large or even infinite leverage advantage to a force which tends to hold the support up (the movement of arm 50 is large cpmpared with the corresponding movement of locking head 55 and the coupler); and in the position of Fig. 2 reverses the leverage ratio so that then a large or infinite leverage advantage is given to the force tending to open the coupler or hold it open (the movement of the coupler is large compared with the corresponding movement oi? the control arm and support).

In the particular cam-linkage design which has been described, the change between those two extremes of leverage ratio is more or less gradual; that is, an intermediate position is reached where the opening coupler can force the movement of the support (e. g. dotted line position of Fig. 2) before the final position is reached in. which coupler movement causes little or no support movement. 'Ihat feature of my invention, involving a linkage having a ratio which varies l more or less gradually between the two extremes,

I conceive to be a broad feature not necessarily, limited to a cam-linkage such as here illustrated.

Fig. 5 shows in diagram a slightly variant form in which the gradual change of leverage ratio in the linkage is emphasized. In that ligure the camming face 58e on the rear edge of control arm 50c is made of such shape as to merge gradually into'the concentric face 60 at the outer end. By so shaping the camming face, the camming angle between 58e and the arcuate movement of head 55 graduallydecreases to zero as the headpasses onto arcuate face 60.

On the other hand certain improvement features of my invention, having to do with the simplicity achieved by utilizing two swinging arms (50 and 56) with a simple cam action between them, may not necessarily be limited to utilizing the forcing action which has been described; that is, the interaction of the two swinging arms may A besimply one of mutual interlocking. Such an about arm pivot 5l. As will be seen from the iigure, head 55h will remain positively locked in its position where the coupler is fully closed until control arm 50h has fully or substantially reached its iinal position, shown in dotted lines in Fig. 6. Then the coupler can immediately open to its dotted line position. In this form of interaction, the arm 50h locks the coupler fully closed until the support is fully in operative position; and then just as soon as the coupler starts to open it completely locks the support.

1.l In a tractor and semi-trailer combination in which the tractor and trailer are provided with inter-engaging draft elements including a draft lock element on one vehicle operable to lockingly engage the draft element of the other vehicle and movable between open and closed positions, the trailer being provided with a support movable between supporting and non-supporting positions; interlocking mechanism acting between the movable support and the draft lock element and including means whereby the draft lock element ispositively locked closed by virtue of the support being in non-supporting position and associated means whereby the support is positively locked in supporting position by virtue of the draft lock element being open,y the draft lock element being movable in a closing directiony without restraint by the interlocking mechanismr andthe support being movable toward its supporting position without restraint by the interlocking mechanism, and motion transmitting means 'associated with said interlocking mechanism and acting to forcibly move the support toward its supporting position by virtue of opening movement of the draft lock element.

- 2. In a tractor and. semi-trailer combination in which-the tractor and trailer are provided with interengaging draft elements including a draft lock element on one vehicle operable to lockingly engage the draftelement of the other vehicle and movable between open and closed positions, the trailer being provided with a support movable between supporting and non-supporting positions; interlocking mechanism acting between the movable support and the draft lock elementwhereby the position of the support is controlled by the position of the draft lock element, said interlocking mechanismincluding a control element connected with the support to move therewith, a locking mem-ber separate from the control element connected with the draft lock element to move therewith, said locking member cooperating with the control element when the draft lock element is open to positively lock the control element in its position corresponding to supporting position of the support, the draft lock element being movable in a closing direction without restraint by the interlocking mechanism and the support being movable toward its supporting position without restraint by the interlocking mechanism, and means coacting between the control element and the locking member and adapted to forcibly move the control element in its direction corresponding to movement of the support to supporting position when the draft lock element moves toward open position.

3. Interlocking mechanism as defined in claim 2, and in which the coacting means is a cam mechanism.

4. In a tractor and semi-trailer combination in which the tractor and trailer are provided with interengaging draft elements including a draft lock element on one vehicle operable to lockingly engage the dra-ft element of the other vehicle and movable between open and closed positions, the trailer being provided with a support movable between supporting and non-supporting positions;

Y interlocking mechanism acting between the movable support and the draft lock element whereby the draft lock and the support are mutually lockingly controlled each by the position of the other, said interlocking mechanism including a control element connected with the support to move therewith, a locking member separate from the control element connected with the draft lock element to move therewith, said locking member cooperating with the control element when the draft lock element is open to positively lock the control element in its position corresponding to supporting position of the support, and said control element cooperating with the locking member when the support is` in noli-supporting position to positively lock the draft lock element closed, and means coacting between the control element and thelocking member and adapted to forcibly move the control element in its direction corresponding to movement of the support to supporting position when the draft lock element moves toward open position.

5. Interlocking mechanism as defined in claim 4, and in which the draft lock element is movable in a closing direction and the support is movable toward its supporting position without restraint by the interlocking mechanism.

6. In a tractor and semi-trailer combination in which the tractor and trailer are provided with interengaging draft elements including a draft lock element on one vehicle operable to lockingly engage the draft element of the other vehicle and movable between open and closed positions, the trailer being provided with a support movable` between Supporting' and non-supporting positions; interlocking and inter-controlling mechanism acting between the movable support `and the draft lock element whereby the position of the support is controlled by the position of the draft lock element, said mechanism including a control element connected with the support to move therewith and a locking member separate from the control element connected with the draft lock element to move therewith, and cooperating camming surfaces on the control element and locking member operating to forcedly move the control member toward its position corresponding to supporting position of the support as the draft lock element opens, said camming surfaces being shaped to increase the mechanical advantage of the locking member over the control element to a substantially infinite ratio as the draft lock element approaches its open position, the draft lock element being movable in a closing direcvtion without restraint-by the interlocking mechanism and the support being movable toward its supporting position without restraint by the 1nterlocking mechanism.

7. In a tractor and semi-trailer combination in whichjthe tractor and trailer are provided with interengaging draft elements including a draft lock element on one vehicle operable to lockingly engage the draft element of the other vehicle and movable between open and closed positions, the trailer being provided with a support movable between supporting and non-supporting positions; interlocking and inter-controll ling mechanism acting between the movable support and the draft lock element whereby the support and element are mutually controlled each by the position of the other, said mechanism including a control element connected with the support to move therewith and a locking member separate from the control element connected with the draft lock element to move therewith, and cooperating camming surfaces on the control s element and locking member operating to forcedly move the control member toward its position corresponding to supporting position of the support as the draft lock element opens, said camming surfaces being shaped to increase the mechanical advantage of the locking member over the control element to a substantially infinite ratio as the draft lock element approaches its open position, and also being shaped to increase -the mechanical advantage of the control element over the locking member to a substantially infinite ratio as the control member reaches its position corresponding to non-supporting position of the support.

8. Interlocking mechanism as defined in claim 2, and in which the control element isa swinging arm connected to the support, the locking -member is a swinging member engaging a face of the swinging arm, and the coacting means comprises a cam formation on the face of the control element engaged by the locking member.

9. In a tractor and semi-trailer combination in which the tractor and trailer are provided with interengaging draft elements including a draft lock element on one vehicle operable to lockingly engage the draft element of the other vehicle annees sitions; interlocking and controlling mechanism acting between the movable support and the draft lock element, saidmechanism comprising a swinging control arm pivoted on one vehicle and connected with the support to swing between two predetermined positions as the support moves between supporting and non-supporting positions, a locking arm swinging on a pivot non-concentric with the control arm pivot and connected to the draft lock element to swing between two predetermined positions as the lock element moves between open and closed positions, and means acting between the two swinging arms whereby the former when in its non-supporting position holds the latter in its draft-lock-closed position, and whereby the latter in its draft-lock-open position holds the former in its supporting position.

10. Interlocking and controlling. mechanism as defined in claim 9, and in which the last mentioned means comprises a locking head on the swinging locking arm, and an edge face formation on the swinging controlling arm engaged by said locking head.

11. In a tractor and semi-trailer combination in which the tractor and trailer are provided with interengaging draft elements including a draft lock element on one vehicle operable to lockingly engage the draft element of the other vehicle and movable between open and closed positions, the trailer being provided with a support movable between supporting and non-supporting positions; interlocking and controlling mechanism acting between the movable support and the draft lock element, said mechanism comprising a. swing- .ing control arm pivoted on one vehicle and connected with the support to swing between two predetermined positions as the support moves between supporting and non-supporting positions, a swinging locking arm pivoted on the same vehicle on a pivot non-concentric with the control arm pivot and connected with the draft loc-k element. to swing between two-predetermined positions as the lock element moves between open and closed positions and having a, locking head which engages and rides one edge face of the swinging control arm, the control arm edge face near the outer end of the arm being substantially concentric with the locking arm pivot when the control arm is in its position corresponding to the supporting position of the support, and the control arm edge face near its pivot lying at an abrupt angle across the line of movement of the locking head when the control arm is in its otherr stated positions.

12. In a tractor and senil-trailer combination in which the tractor and trailer are provided with interengaging draft elements including a draft lock element on one vehicle operable to lockingly engage the draft element of the other 1'4 draft lock element to swing between two predetermined positions as thelock element moves between open and closed positions and having a locking Vhead which engages and rides one edge face of the swinging control arm, the control arm edge face near the outer end of the arm being substantially concentric with the locking arm pivot when the control arm is in its position corresponding to the supporting position of the support, and the control arm edge face near its pivot A lying at an abrupt angle across the line of movement ofthe locking head when the control arm is in its other stated positions, and the intermediate portion of the control arm edge face lying at progressively decreasing angles across the line of movement of the locking head as the control arm moves from its last mentioned position-toward its rst mentioned position.

13. In a tractor and semi-trailer combination 'in which the tractor and trailer are provided with interengaging draft elements including a draft lock element on one vehicle operable to lockingly engage the draft element of the other vehicle and movable between open and closed positions, the trailer being provided with a support movable between supporting and non-supporting positions, said draft lock element comprising a swinging coupler jaw pivotally mounted on the trailer; interlocking and controlling mechanism acting between the movable support and the draft lock element, said mechanism comprising a swinging arm connected directly to the swinging coupler jaw to swing therewith between open and closed positions, a locking head on the end of the locking arm, a swinging control arm pivoted on the trailer at a point non-concentric with the pivot of the coupler jaw, means connecting the swinging control arm with the support to move therewith between two positions corresponding respectively to the supporting and nonsupporting positions of the support, and a cam formation on the control arm adapted to be engaged `and followed by the locking head during the movements of the two arms.

14. In a tractor and semi-trailer combination in which the tractor and trailer are provided with interengaging draft elements including va draft lock element on one vehicle operable to lockingly engage the draft element of the other vehicle and movable between open and closed positions, the trailer being provided with a support movable between supporting and non-supporting positions, said draft lock element comprising a swinging coupler jaw pivotally mounted on the trailer;rinterlocking and controlling mechanism acting between the movable support and the draft lock elements, said mechanism comprising -a v swinging arm connected directly to the swinging coupler jaw to swing therewith between open and closed positions, a swinging control arm pivotally mounted on the trailer at a point non-concentric with the pivotvof the coupler jaw, means connecting said control arm with the support to move therewith between two positions corresponding respectively to the supporting and nonsupporting positions ofthe-support, and interengaging and cam-and-follower formations on the two said arms.

15. In a tractor and semi-trailercombination in which the tractor and trailer are provided with interengaging draft elements including a draft lock element on one vehicle operable to lockingly engage the draft element of the other vehicle and movable between open and closed positions, the trailer being provided with a support mov- A a 15 able between supporting and non-supporting positions; controlling mechanism for the draft lock element and the support, including an interlocking mechanism acting between the support and REFERENCES CITED The following references are of record in the .ille of this patent:

the draft lock element to' lock the latter closed 5 UNITED STATES PATENTS Number Name Date Reid Dec. 28, 1926 Edwards Apr. 16, 1935 Book Nov. 14, 1939 

